Stock & Custom Aluminum Washers

At the same dimensions, an aluminum washer weighs roughly one-third what a steel washer weighs. That weight saving is the primary reason engineers specify aluminum. Willie Washer stamps aluminum flat washers in stock sizes and to customer prints, with plain and anodized finishes available. Every part is produced at our Elk Grove Village plant under ISO 9001:2015.

Why Choose Aluminum Washers

Weight is the headline property, but it isn’t the only one. Aluminum forms a natural oxide layer that provides corrosion resistance without plating, and anodizing thickens that layer while allowing color coding for assembly identification. Aluminum is non-magnetic, which matters in sensor and instrument assemblies. It also conducts electricity and heat well, at a lower cost and weight than copper.

The tradeoff is hardness. Aluminum is softer than steel or stainless, so under high clamp load, an aluminum flat washer can deform or embed rather than distribute the load. Where preload is high, either increase the thickness and bearing area or specify a hardened washer instead.

Where Aluminum Washers Are Used

Aerospace and defense programs specify aluminum wherever mass carries a cost, which is nearly everywhere on an airframe. Automotive and EV assemblies use it for the same reason, as do electrical enclosures where the washer carries both current and load. 

Solar mounting, HVAC equipment, marine topside hardware, and portable equipment all draw on the same combination of low weight and corrosion resistance.

Galvanic Compatibility

This is the one design consideration that causes most aluminum washer problems in the field. Aluminum is anodic to both steel and stainless steel. Put an aluminum washer against a stainless fastener in a wet or humid assembly, and the aluminum corrodes preferentially, sometimes quickly.

Two solutions work: 

1. Match the washer to the surrounding material to maintain galvanically consistent assembly. 
2. Break the electrical path with a non-metallic washer between the dissimilar metals. 

Anodizing also helps by adding a dielectric layer, though it isn’t a substitute for isolation in a saltwater environment.

Sizes, Thicknesses, and Finishes

We stock aluminum flat washers across a wide range of inside diameters, outside diameters, and thicknesses, with parts available plain or anodized. Filter our flat washer catalog by material, dimension, and finish to find a stocked part, or check our full flat washers category for other configurations.

Custom Aluminum Washers

When a stock part doesn’t fit the application, we produce aluminum washers to print. Our tooling department builds dies in-house, and more than 50 presses, plus CNC turning and laser cutting, cover custom inside and outside diameters, non-standard thicknesses, special shapes, and edge treatments. 

Quantities run from a single prototype through several million pieces, with standard lead times as short as four weeks. Incoming aluminum receives spectrographic analysis, and finishes are verified by XRF as part of our quality program.

Frequently Asked Questions About Aluminum Washers